EXAMPLES OF THE FOUR METHODS. 303 



3d. Mnscular exercise, prolonged to exhaustion, diminishes the muscu- 

 lai' irritability. This is a well-known truth, dependent on the most gener- 

 al laws of muscular action, and proved by experiments under the Method 

 of Difference, constantly repeated. Now, it lias been shown by observa- 

 tion that overdriven cattle, if killed before recovery from their fatigue, 

 become rigid and putrefy in a surprisingly short time. A similar fact has 

 been observed in the case of animals hunted to death ; cocks killed during 

 or shortly after a fight ; and soldiers slain in the field of battle. These va- 

 rious cases agree in no circumstance, directly connected with the muscles, 

 except that these have just been subjected to exhausting exercise. Under 

 the canon, therefore, of the Method of Agreement, it may be inferred that 

 there is a connection between the two facts. The Method of Agreement, 

 indeed, as has been shown, is not competent to prove causation. The pres- 

 ent case, however, is already known to be a case of causation, it being cer- 

 tain that the state of the body after death must somehow depend upon its 

 state at the time of death. We are, therefore, warranted in concluding that 

 the single cii'cumstance in which all the instances agree, is the part of the 

 antecedent which is the cause of that particular consequent. 



4th. In proportion as the nutrition of muscles is in a good state, their 

 irritability is high. This fact also rests on the general evidence of the 

 laws of physiology, grounded on many familiar applications of the Method 

 of Difference. Now, in the case of those who die from accident or vio- 

 lence, with their muscles in a good state of nutrition, the muscular irrita- 

 bility continues long after death, rigidity sets in late, and persists long 

 without the putrefactive change. On the contrary, in cases of disease in 

 which nutrition has been diminished for a long time before death, all these 

 effects are I'eversed. These are the conditions of the Joint Method of 

 Agreement and Difference. The cases of retarded and long continued 

 rigidity here in question agree only in being preceded by a high state of 

 nutrition of the muscles ; the cases of rapid and brief rigidity agree only 

 in being preceded by a low state of muscular nutrition ; a connection is, 

 therefore, inductively proved between the degree of the nutrition, and the 

 slowness and prolongation of the rigidity. 



5th. Convulsions, like exhausting exei'cise, but in a still greater degree, 

 diminish the muscular irritability. Now, when death follows violent and 

 prolonged convulsions, as in tetanus, hydrophobia, some cases of cholera, 

 and certain poisons, rigidity sets in very rapidly, and after a very brief du- 

 ration, gives place to putrefaction. This is another example of the Meth- 

 od of Agreement, of the same character with No. 3. 



6th. The series of instances which we shall take last, is of a more com- 

 plex character, and requires a more minute analysis. 



It has long been observed that in some cases of death by lightning, ca- 

 daveric rigidity either does not take place at all, or is of such extremely 

 brief duration as to escape notice, and that in these cases putrefaction is 

 very rapid. In other cases, however, the usual cadaveric rigidity appears. 

 There must be some difference in the cause, to account for this difference 

 in the effect. Now, "death by lightning may be the result of, 1st, a syn- 

 cope by fright, or in consequence of a direct or reflex influence of light- 

 ning on the par vagum ; 2d, hemorrhage in or around the brain, or in the 

 lungs, the pericardium, etc, ; 3d, concussion, or some other alteration in 

 the brain ;" none of which phenomena have any known property capable of 

 accounting for the suppression, or almost suppression, of the cadaveric ri- 

 gidity. . But the cause of death may also be that the lightning produces 



